TR&D 1 Quantitative MRS of the brain at 3T and 7T Principal investigators: Peter B. Barker, D.Phil., Professor of Radiology and Oncology Richard Edden, Ph.D., Associate Professor of Radiology SUMMARY Magnetic resonance spectroscopy (MRS) offers a unique, non-invasive way of studying human brain metabolism and neurochemistry in vivo. Such measurements offer insights into the pathophysiology of human disease, the study of brain function, as well as diagnostic and prognostic information in clinical practice. The needs for new and improved MRS technology are driven by multiple collaborative projects, ranging from the developing brain (i.e. pediatric applications such Autism spectrum disorder and attention deficit hyperactivity disorder) to neurodegenerative disorders (Alzheimer's disease (AD), Huntington's disease), as well as brain tumors, HIV infection, and schizophrenia. The use of high magnetic field strengths such as 7 Tesla is particularly beneficial for MRS; aim 1 of this TR&D will therefore be focused on the development of quantitative methods for spectroscopic imaging (MRSI) at 7T, with an emphasis on methods for rapid, high-resolution metabolite mapping with extended brain coverage. We will focus on mapping of glutamate in the brain using MRSI, and compare the results with those obtained from TR&D2 using novel exchange transfer imaging (ETI) techniques. In recent years, there has been much interest in the measurement of the primary inhibitory neurotransmitter, GABA, in the human brain; this and other metabolites (such as glutathione and the oncometabolite 2-hydroxygltarate) are best measured at 3 Tesla using spectral-editing techniques. Aim 2 of this proposal will focus on quantitative spectral-editing methods, with a particular emphasis of the development of multi-voxel editing methods. Finally, aim 3 will develop quantitative MRS and MRSI methods and post-processing software; the tools developed will be made available for dissemination to the scientific community.